In recent years, a high refractive index film has been employed for adjusting the refractive index in a portable display or building material glass. A representative example of a high refractive index target is a titanium oxide target, but its resistance value is extremely high, and it has a problem that DC sputtering with high mass productivity is thereby difficult. To deal with this problem, a technology to enable DC discharge by lowering the resistivity by addition of a very small amount of a dopant, has been reported (see e.g. Patent Document 1). However, titanium oxide-type oxide material has a strong binding strength between titanium and oxygen and thus is not readily atomized during sputtering, whereby it has a problem that the film-deposition rate is extremely slow.
Further, as a high refractive index target, a sintered composite oxide comprising zinc, aluminum and titanium, has also been reported (see e.g. Patent Document 2). A zinc oxide-type target containing titanium is reported to be adapted to obtain a sintered composite oxide which achieves a high refractive index of 2.0 or more and which has a stable DC discharge performance with little arcing.
However, in recent years, adoption of a cylindrical target capable of applying a high power load, has progressed, and film-deposition wherein a high power which has not been heretofore expected, is applied, is becoming mainstream. Therefore, there is an increasing need for a high refractive index target capable of stable DC discharge which is free from arcing or target cracking even when a high power is applied.